var ipt = document.querySelector('.ipt');
var message = document.querySelector('.message');
ipt.onblur = function () {
    if (this.value.length < 6 || this.value.length > 16) {
        message.className = 'message wrong'
        message.innerHTML = '输入错误,请输入6~16位的密码'
    } else {
        message.className = 'message right'
        message.innerHTML = '输入正确'
    }
}